As is well known in the art, cylinder products use piston and rod components that are attached to each other by various methods. One such method is peening. Peening requires forces axial to the rod in order to deform material from the rod to interfere with a chamfered area of the back of the piston. During the attachment process these forces have to be countered. The force can be frictionally countered on the outer diameter (OD) of the rod, but this may result in marring of the rod surface. If the rod surface is marred, the operation of the piston/rod assembly can be negatively affected. Alternatively, the force can be opposed at the opposite end of the rod, which can result in column loading of the rod and the potential for bending, particularly when subjected to forces necessary to cause adequate deformation for high strength applications.
Another prior art assembly method for attaching the piston to the rod uses a threaded joint. Assembly is effected by simple rotation of the piston and rod relative to one another. During assembly of the piston on the rod, the unthreaded portion of the rod typically acts as a pilot for centering the piston on the rod. The piston and rod may be torqued relative to one another to provide an assembled joint of a desired strength, and a set screw or pin may be installed tangentially to the threaded area of the joint to lock the piston and rod against relative rotation. In order to provide a pressure tight seal between the piston and the rod, and further to add strength to the assembled joint to prevent the parts from separating during operation, an adhesive heretofore has been used at the threaded joint. This, however, usually requires the mating surfaces of the piston and rod to be clean to obtain proper adhesion between the piston and rod. The cleaning process is costly, primarily because of the time needed to clean the parts. In addition, further time is needed to allow the adhesive to properly cure before the assembly can be further assembled with other components of a pneumatic or hydraulic cylinder.